Children who are abused or neglected show impairments in cognitive development in adolescence, a large, population-based study found.

Action Points

Point out that both neglect and abuse in childhood were independently associated with an adverse cognitive outcome in adolescence, and that children who experienced both abuse and neglect were doubly affected.

Note also that the large dropout from the study of abused or neglected children suggests that the results actually underestimate the association between child maltreatment and adverse cognitive outcome.

Children who are abused or neglected show impairments in cognitive development in adolescence, a large, population-based study found.

When tested for literacy skills at age 14, children who had been reported to authorities for either abuse or neglect had a mean difference of −4.4 points out of 100 (standard deviation 15, 95% CI −6.3 to −2.5) compared with children who had not been maltreated, according to Ryan Mills, MPH, of the University of Queensland in Australia, and colleagues.

In addition, on testing for abstract reasoning ability, abused or neglected children had a mean difference of −4.8 points (95% CI −6.7 to −2.9), the researchers reported online in Pediatrics.

There has been much interest in evaluating various outcomes associated with child abuse, including academic achievement, with studies consistently showing poorer performance.

However, less emphasis has been placed on child neglect -- which represents more than half of U.S. cases of maltreatment -- despite research suggesting abnormalities in brain development in infants and animal models experiencing early-life sensory deprivation.

To prospectively explore these concerns, adjusting for potentially contributory family and social factors, Mills and colleagues investigated outcomes for children whose mothers were enrolled in the Mater University Study of Pregnancy between 1981 and 1983.

The 7,223 participating mothers were interviewed at their first antenatal visit, then shortly after delivery, and again when the children reached five years.

Slightly more than half of the children were available for evaluation at 14 years, when they completed the Wide Range Achievement Test and Raven's Standard Progressive Matrices examination.

For their analysis, the researchers obtained reports of maltreatment from the Queensland Department of Families, Youth, and Community Care.

They found that 10.9% of the cohort had at some point been the subject of a formal report of abuse or neglect, with 7% having been substantiated.

More than 60% of abused or neglected children -- a disproportionately high number, according to the authors -- had been lost to follow-up and failed to complete either of the tests.

"In this cohort, the subjects who were lost to follow-up were consistently of more adverse socioeconomic background than those who were tested at the age of 14 and at the same time were more likely to have been reported as cases of abuse or neglect," the researchers observed.

Multiple other variables including maternal age, race, marital status, and tobacco or alcohol use also were significantly (P<0.001) associated with children having been lost to follow-up.

Among the 3,796 children who underwent the testing at age 14, 7.9% had been reported to the agency.

A total of 6.8% had been reported for suspected abuse and 4% for suspected neglect. Three quarters of those reported for suspected neglect had also been reported for abuse, according to the researchers.

When the researchers analyzed test score outcomes according to whether the children were abused or neglected, they found a difference in reading scores in those who were neglected of −5.1 (95% CI −7.7 to −2.4) compared with those who were not maltreated.

For those who were abused, the difference in reading scores was −4.3 (95% CI −6.3 to −2.3).

Their findings of adverse cognitive consequences for both abuse and neglect "support the notion that child neglect has developmental effects that are independently at least as deleterious as abuse, which has important implications for the allocation of resources into additional research into, and prevention of, child neglect," they wrote.

The "significant cognitive disadvantage" experienced by these children is likely to have profound effects on their adult lives, and much work is needed to identify preventive interventions to "interrupt this trajectory of disadvantage," they concluded.

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